Valeant Pharmaceuticals International Inc. last month sweetened its offer for the Irvine company to about $53 billion in cash and stock, but Allergan chief David E.I. Pyott said in a statement Tuesday that it was still not good enough.

"Valeant's revised proposal substantially undervalues Allergan, creates significant risks and uncertainties for Allergan's stockholders and does not reflect the company's financial strength, future revenue and earnings growth or industry-leading R&D," Pyott said in a statement.

The most recent offer, coming after the bid was increased twice last month, would include $72 in cash and 0.83 shares of Valeant stock for each Allergan share. That would amount to about $177 a share for Allergan.

Allergan's stock was down about 0.5% to $163.39 at 11 a.m. PDT.

Valeant, which partnered with activist investor Bill Ackman in the offer, said in a statement that it intends to take the acquisition "directly to [Allergan] shareholders."

"Allergan’s board continues to throw out inaccurate and misleading statements about Valeant and is recycling the same unsupported arguments about Valeant that have already been addressed," Valeant said in a statement released by company spokeswoman Laurie Little.

"Valeant’s offer to combine with Allergan will create substantial value for both companies’ shareholders, and we look forward to giving Allergan shareholders the opportunity to speak for themselves regarding their support for this transaction."

Pyott has said that Allergan's potential for future growth makes it more valuable than Valeant's offer.

A key point of contention is Valeant's suggestion that it would slash research-and-development spending at Allergan, a move that it said would increase its profits and benefit shareholders. Such a move would eliminate hundreds of high-paying science and research jobs at the company.

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